1. Technical Field
The present invention relates to a pneumatic structural element.
2. History of the Related Art
Such, usually beam-like, pneumatic structural elements and also those having a surface formation have become increasingly known over the last few years. These are mostly attributed to EP 01 903 559 (D1). A further development of said invention is provided in WO 2005/007991 (D2). Here, the compression rod has been further developed into a pair of curved compression rods which can also absorb tensile forces and are therefore designated as tension/compression elements. These run along respectively one surface line of the cigar-shaped pneumatic hollow body. D2 is considered to be the nearest prior art.
The strong elevated bending rigidity of the tension/compression elements loaded with compressive forces is based on the fact that a compression rod used according to D2 can be considered as an elastically bedded rod over its entire length, wherein such a rod is bedded on virtual distributed elasticities each having the spring hardness k.
The spring hardness k is there defined byk=npwhere                k=virtual spring hardness [N/m2]        p=pressure in hollow body [N/m2]with the result that the bending load Fk is obtained asFk=2√{square root over (k·E·I)}[N]where        E=modulus of elasticity [N/m2]        I=areal moment of inertia [m4]        